Ryuuko Matoi is a girl who travels with a single red scissor blade, searching for the wielder of the other blade who killed her father. She arrives at Honouji Academy, a high school that lives in fear. It is ruled over by the fearsome student council, led by the student council president, Satsuki Kiryuuin, who use powerful uniforms to crush anyone in their path. After suffering a crushing defeat at the hands of Satsuki, Ryuuko comes accross a possessed school uniform named Senketsu, who puts himself on Ryuuko, granting her special abilities. Teaming up with Senketsu, Ryuuko stands up against Satsuki and the student council to liberate Honnouji Academy from their iron grip and find out the truth behind her father's murder.

Source: Wikipedia

Only covers around the first half of the anime due to being cancelled.